Centrifugal oil cleaner for internal combustion engines



May 25, 1965 4 p. GIACOSA 3,185,390

CENTRIFUGAL on. CLEANER FOR INTERNAL comsus'riou ENGINES Filed Oct. 31. 1960 5 Sheets-Sheet 1 Fig. 7

May 25, 1965 D. GIACOSA I 3,185,390

CENTRIFUGAL OIL CLEANER FOR INTERNAL COMBUSTION ENGINES Filed Oct. 51. 1960 5 Sheets-Sheet 2 Fig 2 v P/P/ R 4P7 D. GIACOSA May 25, 1965 CENTRIFUGAL OIL CLEANER FOR INTERNAL COMBUSTION ENGINES Filed 001'. 31, 1960 5 Sheets-Sheet 3 y 1965 D. GIACOSA 3,185,390

CENTRIFUGAL OIL CLEANER FOR INTERNAL COMBUSTION ENGINES Filed 001;. 31. 1960 5 Sheets-Sheet 4 1 I I I a I I I I b n: s00-25o0-4500--6 00 n f'm. [repgdfa cycles} y 5, 1965 D. GIACOSA 3,185,390

CENTRIFUGAL OIL. CLEANER FOR INTERNAL COMBUSTION ENGINES Filed Oct. 51, 1960 5 Sheets-Sheet 5 4 P kg/cm mzcumf; 6500 np.m.

United States Patent 3,185,390 CENTRIFUGAL OIL CLEANER FOR INTERNAL COMBUSTION ENGINES Dante Giacosa, Turin, Italy, assignor to Fiat Societa per Azioni, Turin, Italy Filed Oct. 31, 1960, Ser. No. 66,114 Claims priority, application Italy, Get. 31, 1956, 28,698/56, Patent 561,848 1 Claim. (Cl. 233-32) This application is a continuation-impart of application Serial Number 677,659, filed August 12, 1957 and now abandoned. 3

This invention relates to improvements in centrifugal oil cleaners for internal combustion engines, of the type in which oil flows over an outwardly extending radial path followed by a radial path extending towards the cleaner axis.

Oil cleaners of this type are known, which comprise a bowl in the form of a flattened container formed by two halves secured to each other at their periphery. I In these cleaners one bowl-half is rigidly mounted on the end of the crankshaft of an internal combustion engine or on the end of a rotary engine shaft, the other bowl-half is situated forward of said end a certain distance apart. The shaft end extending into the oil cleaner carries a diaphragm or baffle in the form of an annular disc or a centrally bored cup which subdivides the inside of the cleaner into two chambers. The first chamber is situated between the bowl-half secured to the shaft and annular diaphragm and connects, through radial passages, with axial conduits or passageways bored in the shaft periphery. These axial passageways convey the oil to be cleaned to the cleaner. The second chamber is situated between the annular diaphragm or bafile and the other bowl-half and connects with an axial bore in the shaft, through which the previously cleaned oil is discharged from the cleaner.

In oil cleaners of this type a centrifugal and a centripetal flow of the lubricating oil take place in the first and second chambers, respectively.

It is known to provide cleaners of this type with inner ribs adapted to subdivide the cleaner chambers into circular segments, the peripheral portions of which act as impurity storage zones. The portions nearer the axis act as settling or separating zones for impurities. The circular segments connect with the inlet passageways to the cleaner and the oil discharge passageways from the cleaner in association with the centrifugal or centripetal oil flow chamber, respectively.

In known cleaners these ribs are complete and extend from the bottom walls of the bowl-halves to contact the annular baflle. The oil flows within the cleaner through radial conduits sealed from one another. The angular oil velocity substantially coincides in this case throughout with the angular rate of speed of the cleaner bowl.

It is moreover known that a centrifugal field cleaner operating at a constant, uniform angular rate of speed provides a settling power for the suspended particles which exclusively depends upon the intensity of the centrifugal field, density of the fluid and suspended particles, hydraulic radii of the particles, fluid viscosity and velocity. Once these magnitudes and dimensions of the oil flow conduits are known, it is possible to ascertain through the known Stokes relations the radii of the particles above which all suspended particles are centrifuged or cleaned out by a centrifugal cleaner.

However, when, as in use of the cleaner in connection with internal combustion engines, the angular rate of speed of the cleaner bowl, deliveries and oil viscosity are variable within wide limits and the rotational movement is not uniform because of the periodical variations of 3,l85,390 Patented May 25, 1965 torque and torsional vibrations of the crank-shaft. Operating periods also occur during which previously accumulated deposits are recycled, which have not yet firmly adhered to the walls of the cleaner bowl. This reduces the overall cleaner efficiency and isthe cause of deterioration of engine parts which are lubricated by the oil from the cleaner.

Attempts have been made at removing these difficulties in various ways such as by automatically insulating the cleaner throughout or its zone in which only impurities accumulate during low efliciency periods. However, attempts heretofore made resulted in constructional complication of the cleaner and did not lead to appreciable results.

An object of this invention is to provide a centrifugal cleaner suitable for cleaning the lubricating oil supplied to parts of internal combustion engines subject to wear. The cleaner is supported at the end of the crankshaft of an internal combustion engine. A feature of the cleaner according to the invention is its high efliciency which is understood to be the ratio of the weight of impurities withdrawn from a given quantity of lubricating oil which is continuously caused to flow at a constant delivery and over a given period of time through the cleaner which rotates at a constant rate, to the overall weight of impurities initially contained in said quantity of oil.

Another object of the present invention is to provide a cleaner of the type referred to above, which is simple and cheap in construction and has an improved overall efficiency over known cleaners, when operating conditions are widely variable as this is the case when the cleaner is used in connection with internal combustion engines.

Still another object of the invention is to provide a cleaner of the type referred to above, of a structure adapted to prevent, during given operational periods of the cleaner, previously accumulated deposits to be recycled when the deposits have not yet firmly adhered to the walls of the cleaner bowl.

Lengthy, repeated tests carried out on a large number of cleaners of the above referred type disclosed that a satisfactory efficiency of the cleaner requires the cleaner to be proportioned so that the rate of oil flow through the accumulating zone is kept lower than, or at the utmost equal to one meter per second, the field of the centrifugal force at the cleaner rate of speed correpsonding to idling speeds of the engine being higher than or equal to about 500 metres per second per second.

A further criterion resides in constructing the cleaner in such a manner that at the zones at which the lubricating oil flows centrifugally or centripetally, respectively, or at both of them a circumferential flow of the oil with respect to the cleaner bowl is made possible, and this flow is prevented at the zone in which impurities accumulate.

My invention is not limited to the precise construction and arrangement of parts illustrated and described herein, nor to the various details thereof, since the same can be modified and arranged otherwise in their various details without departing from the spirit and scope of my invention, an embodiment of which is herein described and illustrated without attempting to show all the various forms or variants by which my invention can be carried out.

The invention shall now be described with reference to the drawings, wherein:

FIGURE 1 is a longitudinal section through an improved centrifugal cleaner mounted on an end of the crankshaft of an internal combustion engine,

FIGURE 2 is a di-agrammatical longitudinal section view through a cleaner of the conventional type mounted on the end of a rotary shaft,

FIGURE 3 is a sectional view taken on line IIIIII of FIGURE 2,

FIGURE 4 is a diagrammatical longitudinal view of a centrifugal cleaner carried out along the criteria set out herein,

FIGURE is a sectional view on line VV of FIG- URE 4,

FIGURES 6 and 7 are diagrams illustrating the efiiciency of centrifugal cleaners ascertained under different operational conditions,

FIGURES 8 and 9 are diagrams illustrating the variation in load loss through centrifugal cleaners depending upon the delivery and rate of rotational speed.

In the drawings 1 and 2 denote bowl-halves, respec- 'tively, forming the cleaner bowl. The bowl-halves are joined at their outer periphery by means of bolts 3 as illustrated in FIGURE 1. A resilient packing 4 seals the contact zone of the bowl-halves 1, 2. The bowl-half 1 is formed with a hub 1a and is supported by a forward extension 5a of a crankshaft 5 of an internal combustion engine. The shaft 5 is supported by a crank-case 6 by means of main bearings. A forward bearing 7 is shown in FIG. 1. The hub 1a on the bowl-half 1 of the cleaner is kept from rotating with respect to the extension 5a on the shaft 5 by a key 8. An annular, cup-shaped diaphragm or bafi le 9 rests against the hub portion 1a on the bowl-half 1, in which radial passageways 16 are bored, and is kept against axial displacement together with the bowl-half 1 by a screw-threaded bushing 11 threaded into a tapped seat in the extension 5a. A pulley 12 is formed on the bowl-half 2 for driving of the bowl through a belt 13 from an accessory part of the engine, not shown. The bowl-half 2 is formed, near its axis, with an inner annular ri'o 14 extending into the inside of the cup shaped diaphragm or battle 9 and surrounding a radial flange 11a on the bushing 11. The bowl-half 2 is formed on its inside, at the region surrounded by the rib 14, with a diametrical wing 15 facing an inlet to an axial bore extending through the bushing 11. This axial bore communicates with an axial passageway 16 bored in the extension 5a on the shaft 5, to which lead radial passageways 17 for lubricating the first main bearing 7 and a passageway 18 extending within the shaft 5.

The bowl-half 1 of the cleaner has secured thereto by means of bolts 19 a flywheel for damping torque vibrations. The periphery of the forward extension 5a on the shaft 5 is surrounded, in addition to the hub 1a on the bowl-half 1, by elements axially spaced thereon comprising a gear 21 controlling the engine valve gear, a washer 22 and a stationary ring 23. The ring 23 acts to convey towards the cleaner oil which is delivered to a bore 24 in a member 6 through an inlet conduit 25 connected to an oil pump (not shown).

The periphery of the extension 5a on the shaft 5 is formed with passageways 26 connecting at one end with an inner chamber 27 in the ring 23 and at their other end with the radial passageways 10 bored in the forward portion of the hub 1a on the bowl-half 1. A key 28 secures the gear 21 and washer 22 to the extension 5a on the shaft 5.

Radial ribs 29, are provided on the inside of the bowl-halves 1, 2 of the cleaner. The ribs 29 extend between the outlet from passageways 10 and outer peripheral portion of the bowl-half 1. The ribs 30 extend between the rib 14 and outer periphery of the bowl-half 2 of the cleaner. The ribs subdivide an inside portion in each bowl-half 1, 2 into circular segments, the peripheral regions of which act as storage chambers for any impurities in the oil flowing through the cleaner. The portions of the circular segments nearer the axis with respect to the storage region 31 act as settling or separating zones.

The two bowl-halves l, 2 are preferably cast. The conveyor ribs 29, 30 are made integral with the bowlhalves. However, the bowl-halves could be made from 5 pressed sheet metal of suitable thickness in which case the ribs 29 and 36 would then be separately attached thereto.

The cleaner operates as follows.

Oil is delivered by a pump (not shown) through inlet conduit 25 and flows to the chambers 24, 27, then through axial passageways 26 and radial passageways 10 to the cleaner, more particularly the centrifugal flow chamber confined by the bottom wall of the bowl-half 1 and annular diaphragm 9. Oil then flows over the outer edge of diaphragm 9 and reaches the centripetal flow chamber situated between diaphragm 9 and bowl-half 2 of the cleaner. The oil then reaches near the axis and enters through the axial bore in bushing 11 the axial passageway 16, and flows through radial passageways 17 to the first connecting main bearing 7 and to other bearings, not shown, for the shaft 5 through conduit 18.

Eflectiveness of a cleaner of the above type is largely affected by the structure and arrangement of ribs 29, 30 subdividing the centrifugal flow chamber and centripetal flow chambers, respectively, into a plurality of circular segments.

Where the ribs are complete and extend from the two bowl-halves l, 2 to substantially contact the annular bafile 9, oil flows through radial paths sealed from each other. Its angular velocity coincides throughout with the rate of speed of the cleaner bowl and its velocity relative to the conduit walls is, at any cross section perpendicular to the conduit axis, as indicated by V in FIGURE 2 of the drawings. This means that the oil velocity is of the same order at the settling and impurity storage zones. It will be obvious that at low speed rates of the engine, when the centrifugal field is negligible, while oil deliveries through the cleaner are of considerable values, the previously accumulated deposits tend to be removed.

Whereas if the radial paths of flow are circumferentially interconnected, such as by limiting the height of the ribs 29, 39 so as to leave a smooth annular region 32, at which a circumferential movement of the oil with respect to the cleaner bowl is made possible, the variation of velocity across the conduit axes takes a form as shown in FIGURE 3 by V on the diagram :1 component of circumferential movement simultaneously occurring, its variation being as shown in the diagram by V, FIGURE 5.

This is governed by known laws of fluid dynamics, under which a fluid which is caused to flow through a container of any form follows a path in which the fluid seeks to correspond to the smallest variation in its velocity along the path of travel, if the container is stationary, and seeks to correspond in angular moment or velocity with respect to the rotational axis, if the container performs a rotary motion.

With the rib arrangement as shown in FIGURES 4 and 5 or an arrangement similar thereto, the angular oil velocity at the smooth region decreases with respect to the rate of speed of the bowl as the oil radially proceeds towards the outside of the cleaner, while on its return flow towards the cleaner axis such difference in angular velocity is at first annulled and thereupon changes in sign.

Since to the latter path there corresponds the smallest overall variation in angular moment of the oil, the major oil portion through the cleaner flows through the smooth region adjacent the annular baffle 9. The overall eifect is a slight reduction at any rate of speed in the separating power of the device, while leaving in a relatively quiescent condition the impurity storage chamber 31. This leads to an overall increase in cleaner efiiciency, which is the additional result of the results even at low rates of speed since the oil velocity relative to the bowl in the storage chambers does not reach a sufiicient value enabling the oil to carry along the previously accumulated deposits.

This arrangement gives rise to a load loss increasing with oil delivery, rotational rate of speed of the cleaner and value of the a/ b ratio. Hence, said ratio should be selected to combine a satisfactory cleaning elliciency and an acceptable load loss.

From measurements effected on similar cleaners at different values of the a/ b ratio the diagram shown in FIGURES 6 to 9 were plotted.

FIGURE 6 shows the variation in efficiency It dependently upon the a/b at various constant angular rates of speed of the cleaner.

FIGURE 7 shows the variation in efficiency n of the cleaner depending upon the a/ b ratio at angular rates of speed varying during test from 500 to 6,500 revolutions, along a repeated cycle matching the variation in revolution number of the engine in accordance with average actual operation of the cleaner on a motor vehicle.

FIGURE 8 shows the variation in load loss through the cleaner depending upon the a/b ratio at constant delivery and various rotational speeds.

FIGURE 9 shows the variation in load loss through the cleaner depending upon the a/b ratio at constant rotational rate of speed and various deliveries.

The efii-ciency n of the cleaner is understood, as mentioned above, as the ratio by weight of the impurities separated by the cleaner to total impurities contained in 5 oil liters continuously circulating during a period of N hours at a delivery rate of Q liters per hour through a cleaner rotating at an angular rate of speed of n revolutions per minute.

The diagrams clearly show that the best compromise between satisfactory etficiency and acceptable load losses occurs when the magnitudes a, b according to FIG- URES 4 and 5 at any cross section of the internal cleaner passageways whether the oil flows centrifugally or centripetally, fulfill the condition:

Thus the ratio between the rib height and the spacing thereof from the baffle in said first and second chambers is the order of 0.15 to 0.40 at each cross-section of the chambers.

What I claim is:

In a centrifugal cleaner for filtering lubricating oil of internal combustion engines and the like means defining a rotatable bowl having an inlet passageway for contaminated oil and an axial discharge passageway for purified oil, battle means in the bowl for guiding the incoming oil radially away from the axis of rotation of the cleaner bowl and then radially toward the axis rotation of the bowl, said bafile means being disposed dividing the bowl internally into a first chamber comprising a centrifugal oil flow chamber and a second chamber comprising a centripetal oil flow chamber, radially extending ribs in said first and second chambers subdividing the chambers into circular segments wherein the oil flowing through the cleaner has an angular speed, substantially coinciding with the angular speed of the bowl, said ribs being disposed axially and radially spaced from said baffle means a distance effective to define adjacent said baffle means an annular zone in which the major portion of oil flowing through the cleaner performs a circumferential movement with respect to the bowl without disturbing quiescent oil adjacent the inner periphery of said bowl, and said ribs having a height in which a ratio of said height relative to the space between the ribs and baffle is in the order of 0.15 to 0.40 at each cross-section of the first and second chambers.

References Cited by the Examiner UNITED STATES PATENTS 1,678,272 7/28 Rushmore 184-6 2,417,747 3 47 Flowers 23 3-29 2,799,448 7/57 Lee 23 324 2,865,562 12/58 Burke 233--24 2,984,410 5/61 Giacosa 23332 FOREIGN PATENTS 607,994 4/26 France.

630,986 9/27 France.

113,848 4/ Sweden.

224,71 1 3 43 Switzerland.

M. CARY NELSON, Primary Examiner.

EUGENE F. BLANC-HAR-D, HERBERT L. MARTIN,

Examiners. 

